During the salad days of the Cooper Island Black Guillemot colony, in the late 1980s, there were 200 wooden nest sites, which I had created in the late 1970s with wood left on the island by the Navy two decades earlier. All 200 nests were occupied by breeding pairs and the colony enjoyed high breeding success — in large part due to the close proximity of sea ice and Arctic Cod, the guillemot’s preferred prey. During that time of “no vacancy” status and high prey availability, the colony regularly had over 150 guillemot young fledge in a single year.
Two decades later, in 2009, only one Black Guillemot fledged from Cooper Island out of the more than 180 that had hatched. The near complete nesting failure that year was the low point in what was a tough decade for Cooper Island guillemots. While the decrease in summer sea ice extent had reduced the availability of Arctic Cod and chicks were having a tough time getting by on sculpin, the larger problem was the nestling mortality indirectly related to loss of sea ice. Polar bears began to seek refuge and food on the island as they lost their summer sea ice habitat and the subarctic Horned Puffins investigated the melting and warming waters off northern Alaska. The bears ate large numbers of guillemot chicks while puffins, while prospecting nest cavities, killed a similar amount. The wooden nest sites that had protected generations of guillemots in earlier decades now were easily flipped by bears and invaded by puffins, with devastating effects on the colony’s productivity.
There appeared to be no easy solution to the loss of nestlings. Providing 200 nest sites capable of deterring a hungry polar bear seemed like an impossible task. While I had long ago come to accept a rapidly changing Arctic, I had hoped that a seabird colony that had provided evidence of earlier changes could persist to monitor the even more drastic anticipated changes. While packing some field gear in a heavy duty plastic case in early 2010 it occurred to me that with some modifications these plastic cases might provide a secure nest site for guillemots. Friends of Cooper Island bought ten cases that year and modified them by adding an entrance hole and partition to provide parents access and nestlings a protected nest cavity . The results that year were impressive (see accompanying graph) with almost all of the fledging young being raised in the new nest cases and wooden sites suffering the same problems with bears and puffins as in previous years.
Our 2010 small-scale trial led to a major urban renewal project in 2011 with all of the “historic” wooden nest sites being disassembled and replaced with 150 Nanuk Cases generously donated at cost by the manufacturer, Plasticase, a Canadian firm that happened to use the Inuit word for polar bear to name their brand of heavy duty plastic cases. The response of the guillemots to their new homes was overwhelmingly positive with over one hundred nestlings fledging in 2011. Parent birds clearly felt more secure incubating eggs in the new sites, rarely flushing during nest checks, and loss of nestlings to either bears or puffins was minimal.
The success in 2011 led to Friends of Cooper Island obtaining fifty more Nanuk cases in March of this year to bring the island back to the 200 nest cavities it had in the past. The cases arrived in Seattle in March where they were retrofitted by Jim Gamache and Max Czapanskiy and taken to Alaska Air Cargo for shipment to Barrow. I was surprised when the forklift operator at Alaska Airlines, remembering last year’s shipment, asked me how successful the cases had been at protecting the birds from polar bears.
A few days later Jim Gamache and I traveled to Barrow where with major assistance from the North Slope Borough’s Department of Wildlife Management we made the 25-mile trip out to Cooper Island in early April, over the ice in Elson Lagoon. While wind chills earlier in the week had been as cold as –25 degrees Fahrenheit, we lucked out by picking a day with little wind and temperatures up to almost 10 degrees Fahrenheit.
The island was snow-covered when we arrived and will be until until early June . Thankfully, bears had not broken into the cabin as they have in the past. Snow drifts on the island were 2-4 feet high hiding the colony completely with the cabin the only point of reference on the island. We left the 50 new Nanuk cases next to the cabin and in early June, Max Czapanskiy and I will put them in the colony as the birds are arriving.
It is not clear that the colony will increase to its historical levels, as issues with prey availability still have the potential of reducing productivity irrespective of those related to nest site integrity. Readers of this blog can check in during the summer to see how the additional nest cases are doing — and if you would like to have a personal connection with the project consider sponsoring a Nanuk nest case and receiving reports on the individual birds that occupy the site and their success in raising their young.